“The STM is based on the concept of quantum tunneling. When a conducting tip is brought very near to the surface to be examined, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, and the local density of states (LDOS) of the sample.[4] Information is acquired by monitoring the current as the tip’s position scans across the surface, and is usually displayed in image form. STM can be a challenging technique, as it requires extremely clean and stable surfaces, sharp tips, excellent vibration control, and sophisticated electronics.“

ArcAttack led me here here: http://www.geocities.com/spm_stm/Project.html Interestingly is still up, though geocities is out. It’s a very similar project but uses an osciloscope rather than an Arduino-to-Pc ‘visualizer’, at least here where I am, I can have acces to an osciloscope easier than an Arduino… though I haven’t tried to build it myself yet, got tons of things from college. The point is, they’re very similar, so check it out. Greetings from Colombia. O.o